Subaru Legacy IV (2008 year). Manual - part 670

4AT-28

Differential Gear Oil

AUTOMATIC TRANSMISSION

3. Differential Gear Oil

A: INSPECTION

1) Park the vehicle on a level surface.
2) Remove the oil level gauge and wipe it clean.
3) Reinsert the level gauge all the way. Make sure
the level gauge is inserted correctly and in the
proper orientation.
4) Remove the oil level gauge again, and check the
level of differential gear oil. If the differential gear oil
level is below “L” line, add oil to bring the level up to
“F” line.

NOTE:
To prevent overfilling the differential gear oil, do not
fill oil to the “F” line or more.

B: REPLACEMENT

1) Lift up the vehicle.
2) Remove the differential gear oil drain plug using
TORX

bit T70, and drain the differential gear oil

completely.

CAUTION:
• Immediately after the vehicle has been run-
ning or after idling for a long time, the differen-
tial gear oil will be hot. Be careful not to burn
yourself.
• Be careful not to spill the differential gear oil
on exhaust pipe to prevent it from emitting
smoke or causing fires. If differential gear oil is
spilled on the exhaust pipe, wipe it off com-
pletely.
3) Replace the gasket with a new part and tighten
the differential gear oil drain plug using the TORX

bit T70.

Tightening torque:

Aluminum gasket

44 N·m (4.5 kgf-m, 32.5 ft-lb)

Copper gasket

70 N·m (7.1 kgf-m, 51.6 ft-lb)

4) Lower the vehicle.
5) Fill the differential with differential gear oil from
the level gauge hole.

Recommended gear oil:

<Ref. to 4AT-3, RECOMMENDED GEAR OIL,
SPECIFICATION, General Description.>

Gear oil capacity:

1.1 — 1.3

(1.2 — 1.4 US qt, 1.0 — 1.1 Imp qt)

6) Check the level of differential gear oil. <Ref. to
4AT-28, INSPECTION, Differential Gear Oil.>

(A) Oil level gauge

(B) Upper level

AT-04863

(B)

(C)

(A)

(A) Oil pan

(B) Differential gear oil drain plug

AT-04830

(A)

(B)

4AT-29

Road Test

AUTOMATIC TRANSMISSION

4. Road Test

A: INSPECTION

1. GENERAL PRECAUTION

Road tests should be conducted to properly diag-
nose the condition of automatic transmission.

NOTE:
When performing the test, do not exceed posted
speed limit.

2. D RANGE SHIFT FUNCTION

Check shifting between 1st

mo 2nd mo 3rd mo

4th while driving on normal city streets.

3. D RANGE SHIFT SHOCK

Check the shock level when shifting up during nor-
mal driving.

4. KICK-DOWN FUNCTION

Check kick-down for each gear. Check the shock
level during kick-down at the same time.

5. ENGINE BRAKE OPERATION

• Check the 3rd gear engine brake when shifting
down from 4th to 3rd range while driving in 4th gear
of manual mode [50 — 60 km/h (31 — 37 MPH)].
• Check the 2nd gear engine brake when shifting
down from 3rd to 2nd range while driving in 3rd gear
of manual mode [40 — 50 km/h (25 — 31 MPH)].
• Check the 1st gear engine brake when shifting
down from 2nd to 1st range while driving in 2nd gear
of manual mode [20 — 30 km/h (12 — 19 MPH)].

6. LOCK-UP FUNCTION

• When the accelerator is lightly depressed while
driving on a flat road in “D” range, check that rpm
does not change abruptly.
• Check slip lock-up with following procedure.
Subaru Select Monitor is required for judgement.
Before starting the check, make sure that no DTC
is displayed using the Subaru Select Monitor. If
there is a DTC, perform the corrective action ac-
cording to the DTC. Recheck to see that the DTC
has been cleared, then start the slip lock-up check.
1) The check is to be performed on a flat and
straight road or on a free roller.

NOTE:
• Slip lock-up will not operate when the vehicle is
lifted up off of its wheels, since there is no surface
resistance.
• When checking on the free roller, the driving re-
sistance will be slightly inadequate. It will be easier
to judge if the foot brake is lightly applied while per-
forming the check.
2) Connect the Subaru Select Monitor.

3) Check the ATF temperature using the Subaru
Select Monitor.

NOTE:
• Make sure that the ATF temperature is between
50 — 100°C (122 — 212°F).
• If the temperature is low, warm up the ATF by
running the vehicle.
4) Start the engine, so that the lock-up duty can be
read on the data display of the Subaru Select Mon-
itor.
5) Drive the vehicle at a constant speed of 35 — 40
km/h (22 — 25 MPH).
6) Read the lock-up duty while vehicle is running.

Standard

25 — 45%

NOTE:
• The reading may be slightly lower on a free roller.
• Slip lock-up control is not operating if the lock-up
duty is 5% or less, or when the lock-up duty goes
down immediately after starting to rise. In these
cases, improper ATF or deterioration of the ATF
may be the cause. Check the amount of ATF or re-
place the fluid, then recheck.

7. P RANGE OPERATION

Stop the vehicle on an uphill grade of 5% or more
and shift to the “P” range. Check that the vehicle
does not move when the parking brake is released.

8. NOISE AND VIBRATION

Check for noise and vibration while driving and dur-
ing shifting.

9. TRANSFER CLUTCH

Check for tight corner braking phenomenon when
the vehicle is moved forward with the steering fully
turned.

10.OIL LEAKAGE

After the driving test, inspect for oil leaks.

4AT-30

Stall Test

AUTOMATIC TRANSMISSION

5. Stall Test

A: INSPECTION

NOTE:
The stall test is extremely important in diagnosing
the condition of an automatic transmission and en-
gine. The test is necessary to measure the engine
stall speeds in “R” and “2nd of manual mode”.
Purposes of the stall test:
• Operational check of the automatic transmission
clutch
• Operational check of the torque converter clutch
• Engine performance check
1) Check that the throttle valve fully opens.
2) Check that the engine oil level is correct.
3) Check that the coolant level is correct.
4) Check that the ATF level is correct.
5) Check that the differential gear oil level is cor-
rect.
6) Increase the ATF temperature to 70 to 80°C
(158 to 176°F) by idling the engine for approximate-
ly 30 minutes (with select lever set to “N” or “P”).
7) Place the wheel chocks at the front and rear of
all wheels and apply the parking brake.
8) Move the manual linkage to ensure it operates
properly, and then set to the “2nd gear of manual
mode”.

9) While pressing hard on the foot brake pedal,
slowly depress the accelerator pedal to full throttle.
10) When the engine speed stabilizes, quickly
record the engine speed and release accelerator
pedal.
11) Shift the select lever to “N” range, and cool
down the engine by idling it for one minute or more.
12) If the stall speed in “2nd gear of manual mode”
is higher than specifications, low clutch slipping
and 2-4 brake slipping may occur. To identify this,
conduct the same test as above in “R” range.

AT-02205

4AT-31

Stall Test

AUTOMATIC TRANSMISSION

13) Perform the stall tests with the select lever in
“D” range.

NOTE:
• Do not continue the stall test for 5 seconds or
more at a time (from closed throttle, fully open
throttle to stall speed reading). Failure to follow this
instruction will cause the engine oil and ATF to de-
teriorate and the clutch and brake to be adversely
affected.
• Be sure to cool down the engine for at least one
minute after each stall test with the select lever set
in the “P” or “N” range and with the idle speed of
1,200 rpm or less.
• If the stall speed is higher than the specified
range, attempt to finish the stall test in as short a
time as possible, in order to prevent the automatic
transmission from sustaining damage.

Stall speed (at sea level):

2,200 — 2,700 rpm

Stall speed (at sea level)

Range

Cause

Below specified value

2nd gear on manual mode, R

• Throttle valve is not fully open
• Engine malfunction
• One-way clutch of the torque converter is slipping

Over specified value

• Line pressure too low
• Low clutch slipping
• One-way clutch malfunctioning

• Line pressure too low
• Reverse clutch slipping
• Low & reverse brake slipping

2nd gear of manual mode

• Line pressure too low
• Low clutch slipping
• 2-4 brake slipping

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